Drill.



A. N. JENNINGS.

- DRILL. APPLICATION FILED MAR. 13, 1908,

Patented Nov. 3, 1908. I

OF CENTRAL CITY, KENTUCKY, ASSIGNOR OF ONE-THIRD TO OF LIMA, OHIO.

AARON EDWIN JENNINGS,

GREGORY JENNINGS,

DRILL.

Specification of Letters Patent. Patented Nov. 3, 1908.

Serial No. 120,925.

Application filed March 13, 1908.

the cutters is formed with a curved portion 14 in its edge 11 terminating in a shoulder 15 which is adapted to engage the corner of To all whom it may concern: Be it known that I, AARON EDWIN JEN- residing l NINGS, a citizen of the United States,

at Central City, in the county of Muhlenberg the shoulder 6 w ien the cutter is in expanded and State of Kentucky, have invented a new position, as shown 1n ig. 1. When thecutand useful Drill, of which the following 18 a ters are in closed position, as shown in Flg. 4,

the upper edge 11 in the opposite side from the shoulder 15 abuts against the shoulder 6, thereby limiting the inward movement of the cutter. The cutters 1 are formed adjacent to their lower ends on the outside with a con caved portion 16, and in the rear of the same with a convex portion 17 and the center piece 2 is correspondingly shaped, as shown in Fig. 3, to overlap and fit against the curved ortion of the cutters. This construction also serves in addition to the shoulders and stops mentioned to hold the cutters in fixed osition when they are expanded.

In drilling coal, it has been found to be advantageous to bore a hole of any desired size to start with, and then some distance within said bore to make a bore of greater diameter, thus forming a pocket in which to place the charge of powder for blasting purposes. By this means a larger charge of powder can be used and the likelihood of blowing out the plug of the smaller bore is reduced.

In using the drill and bit herein described, the bit is detached from the shank 3 and the bit for forming a small hole is attached to the shank 3. After the small hole is drilled a sufficient distance, the bit is removed from the shank 3 and the bit constructed in accord ance with this invention is attached to said shank. The bit in closed position, as shown in Fig. 4, is then shoved into the hole to its end, and the drill is then turned, causing the cutters 1 to be expanded to the position shown in Fig. 1, the shoulder 15 of each cutter abutting against the corner of the shoulder 6. By this means a larger hole or pocket may be formed at the end of the smaller hole. When l the drilling is finished, the drill is withdrawn, thereby closing the cutters 1 which meet the end of the small hole and permit the drill to be withdrawn.

What is claimed is z- 1. An exp ansible mining bit for mining drills consisting of a center piece mounted on a shank, and a pair of cutters each pivotally mounted on the sides of said center piece and specification.

This invention relates to drills for mining purposes, and has especial reference to min- 1 ing drills having expansion bits.

The object of the invention is to provide a new and improved detachable expansion mining bit constructed and arranged as hereinafter set forth and claimed.

Referring to the accompanying drawings, in which similar numerals indicate like carts, Figure 1 is a view in elevation of a dril provided with a mining bit constructed in accordance with this invention and showing the bit in ex anded position. Fig. 2 is a lan view in iorizontal section on the line m-x of Fig. 1, showing the bit in expanded osition. Fig. 3 is a plan view showing the bit in expanded position looking towards the shank. Fig. 4 is a view in elevation showing the bit closed. Fig. 5 is a detail view showing the joint for detachably connecting the bit to the shank.

In carrying out this invention, the bit is constructed with two expansible cutters 1, l each pivoted on one side of a center iece 2 which is preferably detachably secure to the shank 3 of a mining drill or anger. The center piece 2 is detachable secured to the shank 8 as follows :The upper end of the center iece 2 is bent to form a web 2 and offsets 5 and the lower end of the shank 3 is formed with a split or cut 4 and bent to form offsets 5 with inclined surfaces 5 to iit over the web 2 as shown in Fig. 5, so that their offset portions 5 may be slid over each other so as to form a lap joint, the ends of the portions 5 of the shank 3 forming shoulders or stops 6 for the cutters 1. The overlapping parts 5 are secured together in any suitable manner, and as here shown by means of a tapering wedge 7 engaging a hole formed by the two holes 8 in the piece 2. and shank 3. The cutters 1 are pivotally secured to the center piece 2 by means of a bolt 9 held in place by a nut 10.

The upper ends of the cutters 1 are formed with a straight edge portion 11 and their lower ends with a curved cutting edge 12 terminating at the outer corner in a cutting. point 13. The upper outer corner of each of formed with a lower curved cutting edge and outside cutting point, said cutters having curved faces conforming to corresponding faces on the center piece and wedging against the same, in combination with a shank having a stop on each side serving to hold the cutters in expanded and closed positions, as herein set forth.

2. A detachable expansion bit for mining drills consisting of a center piece having its combination with a shank having its lower end split and bent to form ofisets, the said oflsets overlapping and being detachably secured together and forming shoulders, and a pair of cutters pivotally mounted on said center piece and provided with shouldered portions adapted to engage the shoulders formed on the shank and be held thereby in expanded and closed positions, as herein set forth.

3. A detachable expansion bit for mining drills consisting of a center piece having its upper end split and bent to form offsets, in combination with a shank having its lower end split and bent to form offsets, the said ofisets overlapping each other, and secured I together, the offsets of the shank forming shoulders, and a pair of expansible cutters, pivotally mounted on opposite sides of said center piece, and provided with shoulders at their upper corners and a curved portion adjacent to the outer upper corner, as herein set forth.

4. An expansible mining bit, consisting of a center bit having its butt bent to form a web and offsets, and a pair of cutters hinged to said bit, one on each side thereof, in combination with a shank having its end split, and bent to form offsets, the offsets of the g each other to form AARON EDWIN JENNINGS.

Witnesses:

DIMIT LAFFOOR, S. O. GAsP. 

